For Vinnie Walsh, 82, of Auburn, Mass., it was “the whole nine yards — the loss of decency, courtesy, compassion, democracy.” Laurae Carpenetti, 54, a physician from the Atlanta suburbs, said that Mr. Trump’s appointment of Robert F. Kennedy Jr. as his top health official was her motivating factor.

Police detained more than 20 people, mostly on curfew violations, on the first night of restrictions in downtown Los Angeles and used crowd-control projectiles to break up hundreds of protesters.